Linear actuator having a clutch for an airline seat

ABSTRACT

A linear actuator includes a first sleeve that rotatable about an actuation axis, and a second sleeve that is at least partially disposed in the first sleeve. The second sleeve is rotatable about the actuation axis and axially moveable along the actuation axis relative to the first sleeve. The actuator further includes a clutch disposed between the first sleeve and the second sleeve. The second sleeve is moveable along the actuation axis between an operative position rotationally coupled to the first sleeve with the clutch and an inoperative position decoupled from the first sleeve. The actuator also includes a spring that is coupled to the second sleeve and configured to maintain the second sleeve in the operative position. An actuation member of the actuator that is at least partially disposed in the second sleeve is operatively coupled to the second sleeve.

The present application generally relates to actuators, and more particularly, to a linear actuator having a clutch for an airline seat.

BACKGROUND

Linear actuators can convert rotational input from a drive source to a linear output for driving an object along a linear path or rotating an object about a pivot. A typical linear actuator includes a drive sleeve with an axial bore, which operatively couples with a correspondingly sized actuation member. The actuation member and the axial bore can be threaded to engage so that rotation of the drive sleeve causes the movement of the actuation member along the axis of the bore. The drive sleeve may include a drive gear on the outer diameter thereof that can engage a drive gear of a motor either directly or through one or more intervening gears of a transmission. The transmission may function to reduce the speed of the motor and increase the drive torque of the drive sleeve. Thus, the motor can rotationally drive the drive sleeve, which in turn linearly actuates the actuation member.

The actuation member is typically coupled to an object that it pushes or pulls to actuate. In actuating the object, the actuation member may encounter a variety of loads associated with the object. For example, the actuation member may be lifting an object when actuated. Therefore, the load experienced by the actuation member is the weight of the object. However, an actuator is typically designed considering the typical loads it may experience during operation. Accordingly, actuators can endure predictable abuses they may encounter during operation. When the actuation member experiences excessive axial loads, it transfers the loads to the drive sleeve through the threaded coupling between itself and the axial bore of the sleeve. Additionally, the loads may be transferred to the bearings that rotationally support the sleeve or the motor that drives the actuator.

An example of a device that uses a linear actuator is a powered reclining seat, such as those used in premium seating sections of commercial passenger aircraft. Powered reclining seats typically recline from a seating configuration to a flat configuration. On long flights, a passenger can recline the seat to a variety of configurations between an upright configuration to a flat configuration. The seat may include a seat back, a seat bottom and a leg rest. The leg rest may be coupled to a linear actuator, that when powered, can move the leg rest to change the configuration of the seat. The passenger may have access to a controller located on the seat handle to recline the seat with the actuator. The controller is connected to the actuator and can operate the actuator. The actuator is typically designed for operational loads encountered by the seat, such as the passengers leg being on the leg rest, the passenger leaning on the leg rest to reposition himself on the seat, or even the passenger pressing on the leg rest as leverage to dismount from the seat. However, if the passenger presses on the leg rest with his foot by a force that exceeds the loads for which the actuator is designed, the actuator may be damaged. The damage to the actuator may lock the seat in one position, hence rendering the reconfiguration function of the seat inoperable.

In view of the above, there is a need for a linear actuator that can withstand large unexpected or unforeseen forces while reducing any damage from such loads. The present invention satisfies these and other needs and provides further related advantages.

SUMMARY OF THE INVENTION

Other features and advantages of the present disclosure will become apparent from the following description of the preferred embodiments, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the disclosure.

A linear actuator constructed in accordance to the teachings of the present disclosure includes a first sleeve that is rotatable about an actuation axis and a second sleeve rotatable about the actuation axis and moveable along the actuation axis between an operative position and an inoperative position. In the operative position, the second sleeve is rotationally coupled to the first sleeve, while in the inoperative position, the second sleeve is decoupled from the first sleeve. The linear actuator further includes an actuation member that is disposed along the actuation axis and operatively coupled to the second sleeve to axially move with rotation of the second sleeve about the actuation axis. The second sleeve is biased toward the operative position.

A seat constructed in accordance with the teachings of the present disclosure includes a first seat section and at least a second seat section that is pivotable relative to the first seat section. The seat further includes a linear actuator that is operatively coupled to any one of the first seat section and the second seat section to pivot the first seat section and the second seat section relative to each other. The actuator includes a first sleeve that is rotatable about an actuation axis and a second sleeve rotatable about the actuation axis and moveable along the actuation axis between an operative position and an inoperative position. In the operative position, the second sleeve is rotationally coupled to the first sleeve, while in the inoperative position, the second sleeve is decoupled from the first sleeve. The linear actuator further includes an actuation member that is disposed along the actuation axis and operatively coupled to the second sleeve to axially move with rotation of the second sleeve about the actuation axis. The second sleeve is biased toward the operative position.

A linear actuator constructed in accordance to the teachings of the present disclosure includes a first sleeve that is rotatable about an actuation axis, and a second sleeve that is at least partially disposed in the first sleeve. The second sleeve is rotatable about the actuation axis and axially moveable along the actuation axis relative to the first sleeve. The actuator further includes a clutch disposed between the first sleeve and the second sleeve. The second sleeve is moveable along the actuation axis between an operative position rotationally coupled to the first sleeve with the clutch and an inoperative position decoupled from the first sleeve. The actuator also includes a spring that is coupled to the second sleeve and configured to maintain the second sleeve in the operative position. An actuation member of the actuator that is at least partially disposed in the second sleeve is operatively coupled to the second sleeve.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmentary perspective view of a linear actuator constructed in accordance with the teachings of the present disclosure.

FIG. 2 is a schematic side view of the actuator of FIG. 1 shown in the operative position.

FIG. 3 is a schematic side view of the actuator of FIG. 1 shown in the inoperative position.

FIG. 4 is a schematic side view of a reclining aircraft seat having a linear actuator constructed in accordance with the teachings of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1-3, an actuator 10 constructed in accordance with the teachings of the present disclosure is shown. The actuator 10 includes a first sleeve 12 that is rotatable about an actuation axis 14. The actuator 10 also includes a second sleeve 16 that is rotatable about the actuation axis 14 and is moveable along the actuation axis 14 relative to the first sleeve 12 between an operative position of the actuator 10 (shown in FIG. 2) and an inoperative position of the actuator 10 (shown in FIGS. 1 and 3). The actuator 10 further includes an actuation member 18 that is operatively coupled to the second sleeve 16. In the operative position, the second sleeve 16 is operatively coupled to the first sleeve 12 and can rotate with the first sleeve 12. Therefore, in the operative position, rotation of the first sleeve 12 rotates the second sleeve 16, which moves the actuation member 18 along the actuation axis 14. The second sleeve 16 is biased toward being operatively coupled to the first sleeve 12 by a biasing force 19. In the inoperative position, the second sleeve 16 is decoupled from the first sleeve 12 so that rotation of the first sleeve 12 does not rotate the second sleeve 16, which does not move the actuation member 18 along the actuation axis 14.

When the actuator 10 is in use, it typically remains in the operative position as long as the biasing force 19 can maintain the operative coupling between the first sleeve 12 and the second sleeve 16 against any opposite loads 20 that may be exerted on the actuation member 18. However, when the load 20 is greater than the biasing force 19, the load 20 moves the second sleeve 16 away from the first sleeve 12 to decouple the second sleeve 16 from the first sleeve 12. Therefore, the actuator 10 provides a safety mechanism by which damage to the actuator 10 is prevented or minimized if the load 20 exceeds the biasing force 19.

The actuator 10 may include a motor (not shown) that can drive the first sleeve 12 with a drive gear 34. The drive gear 34 may be defined by a toothed outer diameter of the first sleeve 12 or may be a separate gear that is mounted over the first sleeve 12, or other methods known in the art to convey the drive force from the motor to the first sleeve 12. The actuator 10 may also include support bearings 36, by which the first sleeve 12 is allowed to rotate about the actuation axis 14, while prevented from any axial movement along the actuation axis 14. The support bearing 36 is fixedly supported by a housing 61 (shown in FIG. 4) of the actuator 10.

The second sleeve 16 includes a first portion 40 and a second portion 42. The first portion 40 has an outer diameter that is smaller than an inner diameter of the first sleeve 12. Accordingly, the first portion 40 can be disposed inside the first sleeve 12 and be freely rotatable about and movable along the actuation axis 14 inside the first sleeve 12. The actuator 10 includes a radial bearing 39 and an axial bearing 41 between the first portion 40 of the second sleeve 16 and the first sleeve 12. The radial bearing 39 permits rotation of the first portion 40 relative inside the first sleeve 12, and the axial bearing 41permits axial translation of the second sleeve 16 relative to the first sleeve 12. The second portion 42 has an outer diameter that is generally larger than the inner diameter of the first sleeve 12. The difference in the outer diameters of the first portion 40 and the second portion 42 defines a circumferential face 43. Accordingly, the second portion 42 cannot be inserted in the first sleeve 12 beyond the circumferential face 43.

The first sleeve 12 also includes a circumferential face 45 that is axially opposed to the circumferential face 43 of the second sleeve 12. The first sleeve 12 includes first clutch coupling 44 mounted on the circumferential face 45. Similarly, the second sleeve 16 includes a second clutch coupling 46 mounted on the circumferential face 43. The first clutch coupling 44 and the second clutch coupling 46 define a clutch 47, by which the second sleeve 16 can rotationally engage with and disengage from the first sleeve 12. In the operative position of the actuator 10, the clutch couplings 44 and 46 are engaged with each other. Accordingly, any rotation of the first sleeve 12 is transferred to the second sleeve 16.

When the clutch couplings 44 and 46 are disengaged, however, as a result of the second sleeve 16 moving away from the first sleeve 12 along the actuation axis 14, any rotation of the first sleeve 12 does not rotate the second sleeve 16. When the second sleeve 16 is in the inoperative position, however, the second sleeve 16 can rotate about the actuation axis 14. Therefore, the actuation member 18 can move along the actuation axis 14 when the second sleeve 16 is in the inoperative position.

To keep the actuator 10 in the operative position, the actuator 10 includes a biasing member 50 that biases the second sleeve 16 toward the first sleeve 12 so that the first clutch coupling 44 and the second clutch coupling 46 remain engaged to each other in the absence of a load 20 that is greater that the biasing force 19 of the biasing member 50. The biasing member 50 is supported by or fixed to a housing 61 (shown in FIG. 4) of the actuator 10. The biasing member 50 may be a spring. In the example shown, the spring 50 is a Bellville spring that is mounted over the second portion 42 of the second sleeve 16 and is supported by an annular plate 51 and a support bearing 53. The support bearing 53 is fixedly supported by the housing 61 of the actuator 10 Accordingly, the spring 50 cannot move axially relative to the second sleeve 16, but can only be compressed or decompressed along the actuation axis 14 in accordance with the axial movements of the second sleeve 16. Although the biasing member 50 is shown herein as a spring, one of ordinary skill in the art will readily appreciate that the biasing member 50 may be any type of device that biases the second sleeve 16 toward the first sleeve 12.

Rotation of the second sleeve 16 about the actuation axis 14 causes axial movement of the actuation member 18 along the actuation axis 14. The inner diameter of the second sleeve 16 is helically geared or threaded to engage corresponding helical gearing or threads of the actuation member 18. One of ordinary skill in the art will readily recognize that the actuation member 18 is typically referred to as a lead screw or worm gear, depending on whether it is threaded or geared, respectively. Additionally, the second sleeve 16 is typically referred to as an ACME nut. The actuation member 18 can be coupled to an object, the actuation of which is desired by moving the actuation member 18 along the actuation axis 14. To axially drive the actuation member 18, the motor (not shown) is powered to rotationally drive the first sleeve 12 as described above. The first sleeve 12 then drives the second sleeve 16 through the clutch 27. Thus, the second sleeve 16 drives the actuation member 18 along the actuation axis 14.

The biasing force of the spring 50 maintains the first clutch coupling 44 in engagement with the second clutch coupling 46. However, should the load 20 exceed the biasing force 19 of the spring 50, the spring 50 will compress and the first clutch coupling 44 will disengage from the second clutch coupling 46. Accordingly, the first sleeve 12 and the second sleeve 16 will become disengaged and the second sleeve 16 will no longer be driven by the first sleeve 12. However, although the second sleeve 16 is disengaged from the first sleeve 12 in the inoperative position, the second sleeve 15 can rotate about the actuation axis 14. Thus, the load 20 on the actuation member 18 can continue to move the actuation member 18 along the actuation axis 14 by the rotational coupling between the actuation member 18 and the second sleeve 16. As will be described in the following, the inoperative position of the actuator 10 can provide a safety system during scenarios when the loads on the actuation member 18 are excessive or beyond safe operational loads of the actuator 10.

During normal use of the actuator 10, the loads 20 exerted on the actuation member 18 may be less than the biasing force 19 of the spring 50. However, depending on the environment in which the actuator 10 is used, large static loads or dynamic loads (e.g., impact loads) that are either expected as part of the operation of the actuator 10 or unexpected during the normal operation of the actuator 10 may be exerted on the actuation member 18. Such loads 20 cause the spring 50 to compress as described above to decouple the second sleeve 16 from the first sleeve 12 by moving the second sleeve 16 away from the first sleeve 12 along the actuation axis 14. Accordingly, such loads 20 will not be transferred through the actuation member 18 to the first sleeve 12, to the drive gear 34, to the motor, or to any other component of the actuator 10 or the object to which the actuator is attached. However, to prevent disturbing the operation of the actuator 10, once the load 20 on the actuation member 18 returns to a level below the biasing force 19 in the spring 50, the biasing force 19 will move the second sleeve 16 toward the first sleeve 12 to engage the first clutch coupling 44 with the second clutch coupling 46. Thereby, the operation of the actuator 10 can resume.

Referring to FIG. 4, application of the actuator 10 for a reclining seat 60 is shown in accordance with the teachings of the present disclosure. The seat 60 may be any type of seat with seating surfaces that can pivot relative to each other to change the seating configuration of the seat. In the seat shown in FIG. 4 and described herein, both the backrest 52 and the leg rest 54 may pivot relative to the seat bottom 56 to a degree such that the seat 60 becomes flat for sleeping purposes. The seat 60, for example, may be the type used for premium seating on commercial airlines where a passenger can recline the seat 60 to a substantially flat position for sleeping during long flights.

The seat includes a plurality of legs 58 for supporting the seat on the floor 59. The actuator 10 can be fixedly mounted beneath the seat bottom 56 or the legs 58 with the actuator housing 61. The actuation member 18 can be fixedly connected to the leg rest 54 or the backrest 52. In certain seats, the leg rest 54 and the backrest 52 may be connected so that pivoting of one relative to the seat bottom 56 will pivot the other. Accordingly, by using the actuator 10 to pivot only the leg rest 54 or the backrest 52, the entire seat can be reconfigured. In the seat 60 of FIG. 4, the actuation member 18 is connected to the leg rest 54.

The seat 60 may include an activation button, lever, or the like, which is generally shown as a lever 62,that a user of the seat 60 can activate to position the seat between the upright position and the flat position. The lever 62 may be part of a controller 63 that is connected to the actuator 10 to operate the actuator 10. In the seat 60 of FIG. 4, when the actuation member 18 is driven toward the leg rest 54, the leg rest 54 pivots upward and causes the seat 60 to move to a flat orientation. When the actuator 10 is operated in reverse, that is when the actuation member 18 is moved toward the actuator 10, the leg rest 54 pivots downward to place the seat 60 in the upright orientation. Thus, a user can activate the actuator 10 in the two possible directions thereof along the actuation axis 14 to place the seat 60 in a desired orientation.

During the use of the seat 60, excessive loads may be exerted on the leg rest 54 by the user. Such excessive loads may be caused by the user utilizing the leg rest 54 for leverage to dismount from the seat 60 or reorient himself on the seat 60. Additionally, such excessive loads may be created by the user stepping on the leg rest 54 or another person stepping on the leg rest 54. Such excessive loads on the leg rest 54 is transferred to the actuation member 18, which can then transfer the load along the actuation axis 14 toward the actuator 10. With the actuator 10 constructed in accordance with the teachings of the present disclosure, however, the excessive load exerted on the leg rest 54 will compress the spring 50 to move the second sleeve 16 away from the first sleeve 12. Accordingly, the first clutch coupling 44 will disengage from the second clutch coupling 46. Thus, the axial load on the actuation member 18 is absorbed by the spring 50. However, because the second sleeve 16 can rotate about the actuation axis 14 when the second sleeve 16 is in the inoperative position, the actuation member 18 can move along the actuation axis 14 even after the clutch couplings 44 and 46 have been disengaged. Therefore, the leg rest 54 can continue to pivot toward a closing position by the load 20 moving the actuation member 18 along the actuation axis 14.

Once the load 20 is removed from the leg rest 54 or reduced to below the biasing force of the spring 50, however, the biasing force in the spring 50 will move the second sleeve 16 towards the first sleeve 12 so that the first clutch coupling 44 engages the second clutch coupling 46. Therefore, as soon as the excessive load is relieved from the leg rest 54, the actuator 10 can operate normally so that the seat 60 can be placed in the upright or flat orientations.

From the foregoing, it will be appreciated that, although the use of the actuator 10 is described herein with respect to the seat 60, the actuator 10 can replace any linear actuator in any device where the actuator may be subjected to excessive loads. The coupling and decoupling of the first sleeve 12 and the second sleeve 16 through the clutch 47 allows any excessive loads that may be exerted on the actuation member 18 to be absorbed by the spring 50. Furthermore, because the spring 50 biases the second sleeve 16 toward operational coupling with the first sleeve 12, the actuator 10 can resume normal operation as soon as the excessive load on the actuation member 18 is removed or lowered to a level below the bias force in the spring 50.

While a particular form of the disclosure has been illustrated and described, it will be apparent that various modifications can be made without departing from the spirit and scope of the disclosure. Accordingly, it is not intended that the disclosure be limited, except as by the appended claims. 

1. A linear actuator comprising: a first sleeve rotatable about an actuation axis; a second sleeve rotatable about the actuation axis and moveable along the actuation axis between an operative position being rotationally coupled to the first sleeve and an inoperative position being decoupled from the first sleeve; and an actuation member disposed along the actuation axis and operatively coupled to the second sleeve to axially move with rotation of the second sleeve about the actuation axis; wherein the second sleeve is biased toward the operative position.
 2. The linear actuator of claim 1, wherein axial movement of the actuation member rotates the second sleeve when the second sleeve is in the inoperative position.
 3. The linear actuator of claim 1, wherein the second sleeve is biased toward the operative position with a spring.
 4. The linear actuator of claim 3, wherein the second sleeve decouples from the first sleeve when the actuation member moves the second sleeve against a bias force of the spring.
 5. The linear actuator of claim 1, wherein the second sleeve frictionally engages the first sleeve in the operative position.
 6. The linear actuator of claim 1, further comprising a first clutch coupling connected to the first sleeve and a second clutch coupling connected to the second sleeve, wherein the first clutch coupling and the second clutch coupling engage in the operative position to rotationally couple the first sleeve to the second sleeve.
 7. The linear actuator of claim 6, wherein the second clutch coupling is biased toward engagement with the first clutch coupling with a spring coupled to the second sleeve.
 8. The linear actuator of claim 7, wherein the second clutch coupling decouples from the first clutch coupling when the actuation member moves the second sleeve against a bias force of the spring.
 9. A seat comprising: a first seat section; at least a second seat section pivotable relative to the first seat section; and a linear actuator operatively coupled to any one of the first seat section and the second seat section to pivot the first seat section and the second seat section relative to each other, the actuator comprising: a first sleeve rotatable about an actuation axis; a second sleeve rotatable about the actuation axis and moveable along the actuation axis between an operative position being rotationally coupled to the first sleeve and an inoperative position being decoupled from the first sleeve; and an actuation member disposed along the actuation axis and operatively coupled to the second sleeve to move along the actuation axis upon rotation of the second sleeve about the actuation axis; wherein the second sleeve is biased toward the operative position.
 10. The seat of claim 9, wherein axial movement of the actuation member rotates the second sleeve when the second sleeve is in the inoperative position so that the second seat section is pivotable relative to the first seat section when the second sleeve is in the inoperative position.
 11. The seat of claim 9, wherein the second sleeve is biased toward the operative position with a spring.
 12. The seat of claim 11, wherein the second sleeve decouples from the first sleeve when the actuation member moves the second sleeve against a bias force of the spring.
 13. The seat of claim 9, wherein the second sleeve frictionally engages the first sleeve in the operative position.
 14. The seat of claim 9, further comprising a first clutch coupling connected to the first sleeve and a second clutch coupling connected to the second sleeve, wherein the first clutch coupling and the second clutch coupling engage in the operative position to rotationally couple the first sleeve to the second sleeve.
 15. The seat of claim 14, wherein the second clutch coupling is biased toward engagement with the first clutch coupling with a spring coupled to the second sleeve.
 16. The seat of claim 15, wherein the second clutch coupling decouples from the first clutch coupling when the actuation member moves the second sleeve against a bias force of the spring.
 17. A linear actuator comprising: a first sleeve rotatable about an actuation axis; a second sleeve at least partially disposed in the first sleeve, the second sleeve being rotatable about the actuation axis and axially moveable along the actuation axis relative to the first sleeve; a clutch disposed between the first sleeve and the second sleeve, the second sleeve being moveable along the actuation axis between an operative position rotationally coupled to the first sleeve with the clutch and an inoperative position decoupled from the first sleeve; a spring coupled to the second sleeve and configured to maintain the second sleeve in the operative position; and an actuation member at least partially disposed in the second sleeve and operatively coupled to the second sleeve.
 18. The linear actuator of claim 17, wherein axial movement of the actuation member rotates the second sleeve when the second sleeve is in the inoperative position.
 19. The linear actuator of claim 17, wherein the second sleeve decouples from the first sleeve when the actuation member moves the second sleeve against a bias force of the spring.
 20. The linear actuator of claim 17, wherein the clutch comprises a first clutch coupling connected to the first sleeve and the second clutch coupling connected to the second sleeve, wherein the first clutch coupling and the second clutch coupling engage in the operative position to rotationally couple the first sleeve to the second sleeve.
 21. The linear actuator of claim 20, wherein the second clutch coupling is biased toward engagement with the first clutch coupling with the spring.
 22. The linear actuator of claim 21, wherein the second clutch coupling decouples from the first clutch coupling when the actuation member moves the second sleeve against a bias force of the spring. 